Integrated energy management system including a fuel cell coupled refrigeration system

ABSTRACT

The disclosure relates to an integrated energy management system for managing thermal and electrical energy in a fuel cell coupled refrigeration system. In one example, a refrigeration cycle is driven by heat provided alternatively by a fuel cell and an electric heating device. In another example, a refrigeration cycle is driven by heat provided by a fuel cell to reduce consumption of electrical grid supplied power.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/492,318 filed on Jun. 1, 2011, entitled “FuelCell Coupled Refrigeration System for Power, Heating and CoolingApplications”, the entire disclosure of which is expressly incorporatedby reference herein.

FIELD OF THE DISCLOSURE

The present disclosure relates to an integrated energy management systemincluding control systems for use with a refrigeration system powderedby a fuel cell, and in particular a proton exchange membrane (PEM) fuelcell. The integrated energy management system is used for regulating theambient temperature of an environment.

BACKGROUND OF THE DISCLOSURE

Heating and cooling systems of different types are commonly used tocontrol ambient temperatures of internal spaces of buildings andvehicles and to cool refrigeration volumes such as transport trailers,refrigerators and freezers. Generally, heating and cooling systemsconsume electrical or mechanical energy to drive a heating and coolingcycle. Some systems, for example heat pumps, include valves adapted toswitch the flow of refrigerant through heat exchangers, referred to ascondensers and evaporators, so that the system can provide heating orcooling depending on the outdoor temperature. For convenience, systemsconfigured to provide heating or cooling by changing the state of afluid medium to transfer heat will be referred to as refrigerationsystems.

Air cooling and vapor-compression are two common refrigeration systems.In air cooling systems, a fan or series of fans causes ambient air toflow over or through the target space. The air absorbs heat andtransfers the heat to an external space. However, the cooling capacitydepends on the air temperature of the ambient air, which can varywidely. As a result, air cooling may be unreliable, particularly intropical and desert environments.

In a vapor-compression refrigeration system, the system transfers heatthrough a fluid refrigerant that is periodically cycled through acondenser and an evaporator. The cooling effect is provided when therefrigerant enters the evaporator, where the refrigerant's phase changesfrom a liquid-vapor mixture to a saturated-vapor at low pressure. Therefrigerant then passes into a compressor where pressure of therefrigerant is increased as it is mechanically compressed and therefrigerant is transformed into a superheated-vapor. From thecompressor, the refrigerant enters into the condenser where the heatpicked up in the evaporator is rejected to the atmosphere, and therefrigerant changes back to a saturated-liquid. The refrigerant thenreturns to its initial liquid-vapor state after passing through anexpansion valve. The energy input to drive the cycle is provided in therefrigerant compression stage. Vapor-compression systems are morereliable than air cooling systems but consume more energy and aregenerally heavier.

Accordingly, there is a need in the art for a more energy-efficient,effective means of powering refrigeration systems. It would be furtheradvantageous if the thermal and electrical energy to be provided to arefrigeration system was provided at a highly efficient, consistentmanner, with little to no gas emissions.

SUMMARY OF THE DISCLOSURE

The present disclosure is directed to generating and managing thermalenergy in a fuel cell coupled refrigeration system. For example, a heatexchanger couples, directly or indirectly, to a fuel cell and a heatdriven refrigeration system to transfer at least a portion of thermalenergy generated by the fuel cell to the refrigeration system, therebydriving a refrigeration cycle of the refrigeration system. In someembodiments, the heat exchanger may further be coupled with an electricheating device such to transfer at least a portion of the thermal energygenerated by the electric heating device to the refrigeration system asan alternative or supplemental thermal energy source from the fuel cell.A control system is coupled with the fuel cell coupled refrigerationsystem to form an integrated energy management system that controlsoperation of the fuel cell coupled refrigeration system.

In one embodiment the present disclosure is directed to an integratedenergy management system for generating and managing thermal energy. Thesystem comprises: a fuel cell operable to generate electric energy andthermal energy; an energy storage device operable to receive at least aportion of the electric energy generated by the fuel cell; arefrigeration system including a refrigerant; a heat exchanger operableto transfer at least a portion of the thermal energy from the fuel cellto the refrigeration system to heat the refrigerant; and a controlsystem operable to control operation of the fuel cell.

In another embodiment the present disclosure is directed to a method ofoperating an integrated energy management system. The method comprisesgenerating electric energy and thermal energy with a fuel cell; storingat least a portion of the electric energy in an energy storage device;and driving a refrigeration cycle of a refrigeration system with energyprovided by a first source of energy and with thermal energy from thefuel cell.

It has been unexpectedly discovered that using thermal energy generatedby fuel cells to drive refrigeration cycles of a refrigeration systemprovides both functional and financial benefits to the user,particularly homeowners. Particularly, the average energy output of thefuel cell is decreased as the electrical load of the HVAC system isdecreased or eliminated, compared to the conventional electricallydriven heating, ventilation, and air conditioning (HVAC) system,enabling a higher efficiency fuel cell operation. Note that fuel cellefficiency for a given fuel cell stack increases as its power leveldecreases. Further, surplus electrical energy generated by the fuel cellcan additionally be used to power the electrical grid of a building orresidence, providing alternative or supplemental electrical energyduring periods when electrical costs are highest for utilities (e.g.,summer months).

Further, an integrated energy management system for controlling theoperation of the fuel cell coupled refrigeration system allows forfurther efficiency in a heating and cooling operation, thereby reducingthe total energy cost to the consumer. Additionally, the integratedenergy management system advantageously operates to recharge orcondition any additional electrical energy storage devices and to reducecompressor load in vapor compression cycles such that the system is ableto attain longer lifetimes than conventional HVAC and energy storagesystems. Moreover, since the fuel cell is able to provide heat generatedfrom the power producing electrochemical reaction, and since this heatcan be used to promote cooling, these can be used to provide temperatureregulation for high cost electrical components such as batteries,control systems, or power electronic devices. Furthermore, since theoutput power of the fuel cell is inherently direct current (DC), it canpower DC or brushless DC electric motors that could power the compressorused in a vapor compression refrigeration cycle, thus further increasingthe efficiency of the refrigeration system and enhancing its life.

Accordingly, the integrated energy management system of the presentdisclosure can be used as an upgrade or alternative to the conventionalHVAC system, which is a high cost appliance, to provide for moreenergy-efficient heating/cooling of an environment.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other disclosed features, and the manner ofattaining them, will become more apparent and will be better understoodby reference to the following description of disclosed embodiments takenin conjunction with the accompanying drawings, wherein:

FIG. 1A is a block diagram of a fuel cell coupled refrigeration systemincluding a fuel cell, a heat driven refrigeration system, and a heatexchanger for use with an integrated energy management system accordingto one embodiment of the disclosure;

FIG. 1B is a block diagram of an integrated energy management systemincluding a fuel cell, a refrigeration system, and an energy storagesystem according to one embodiment of the disclosure;

FIG. 2 is a schematic diagram depicting an absorption refrigerationsystem thermally coupled with a fuel cell for use with the integratedenergy management system according to yet another embodiment of thedisclosure;

FIG. 3 is a schematic diagram depicting the fuel cell coupledrefrigeration system of FIG. 2 thermally coupled with an air pumpdirecting excess heat to a heat load;

FIG. 4 is a schematic diagram depicting a vapor-compressionrefrigeration system thermally coupled to a liquid cooled fuel cell withan auxiliary cooling system for use with the integrated energymanagement system according to a yet further embodiment of thedisclosure;

FIG. 5 is a schematic diagram depicting an absorption refrigerationsystem thermally coupled to a fuel cell and an auxiliary liquid coolingsystem for use with the integrated energy management system according toa further embodiment of the disclosure;

FIG. 6 is a schematic diagram depicting the ejector refrigeration systemfluidly coupled to a fuel cell for use with the integrated energymanagement system according to yet another embodiment of the disclosure;

FIG. 7 is a schematic diagram depicting a compressor fluidly coupled toa fuel cell coupled refrigeration system for use with the integratedenergy management system according to another embodiment of thedisclosure;

FIG. 8 is a schematic diagram depicting a vapor-compressionrefrigeration system thermally coupled to a fuel cell and an auxiliarycooling system for use with the integrated energy management systemaccording to a further embodiment of the disclosure;

FIG. 9 is a schematic diagram depicting an absorption refrigerationsystem thermally coupled to a liquid cooled fuel cell with an auxiliaryliquid cooling system for use with the integrated energy managementsystem according to a yet further embodiment of the disclosure;

FIG. 10 is a block diagram of a fuel cell coupled refrigeration systemincluding a heat driven refrigeration system, a fuel cell and a batterycell stack for use with the integrated energy management systemaccording to another embodiment of the disclosure;

FIGS. 11 and 12 are block diagrams of a fuel cell coupled refrigerationsystem for use with the integrated energy management system in a mobileapplication according to a further embodiment of the disclosure;

FIG. 13 is a graph of an exemplary range extending feature implementedwith an integrated energy management system according to a furtherembodiment of the disclosure; and

FIGS. 14 and 15 are graphs of exemplary comfort features implementedwith an integrated energy management system according to a yet furtherembodiment of the disclosure.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the drawings representembodiments of various features and components according to the presentdisclosure, the drawings are not necessarily to scale and certainfeatures may be exaggerated in order to better illustrate and explainthe present disclosure. The exemplification set out herein illustratesembodiments of the disclosure, and such exemplifications are not to beconstrued as limiting the scope of the disclosure in any manner.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure is directed to an integrated energy managementsystem for managing thermal and electrical energy generated in a fuelcell coupled refrigeration system. Thermal energy generated by the fuelcell can be used to drive a refrigeration cycle of the refrigerationsystem in an energy-efficient operation as an alternative or as asupplement to conventional electrically driven refrigeration systems.Exemplary refrigeration systems include vapor-compression, absorptionand ejector refrigeration systems. The electrical energy generated bythe fuel cell may be provided to an energy storage device or toelectrically drive a primary or supplemental compressor in a vaporcompression cycle or to generate heat through a resistance load to drivean absorption or ejector refrigeration system. Exemplary energy storagedevices include batteries and capacitor banks.

These and other features of the integrated energy management systems andmethods of the present disclosure, as well as some of the many optionalvariations and additions, are described in detail hereafter.

As used herein, the term “heat driven refrigeration system” refers to aheating and cooling refrigeration cycle that eliminates the need for amechanical compressor and instead uses a thermal energy source to drivethe cycle. Exemplary heat driven refrigeration systems include absorbentand ejector refrigeration systems.

As used herein, the term “refrigeration cycle” refers to a model ofmoving heat from one location (“source”) at a lower temperature toanother location (“heat sink”) at a higher temperature using mechanicalwork or thermal work.

As used herein, the term “thermal load” refers to any component ordevice suitable to supply or receive heat. Exemplary thermal loadsinclude electronic components, passenger cabins, battery compartments,electronic circuits, storage compartments, ice makers, dehumidifiers,and the like. The foregoing and later described embodiments describeheat transfer devices which may be referred to as heat exchangers (e.g.,evaporators, condensers and generators).

As used herein, the term “generator” refers to a heat transfer devicewhich thermally couples, directly or indirectly, a refrigeration systemand a fuel cell such that excess heat from the fuel cell may heat therefrigerant of the refrigeration system. In one embodiment according tothe disclosure, a generator includes a body. Embedded in the body are arefrigerant circuit and a heating device. The heating device isconfigured to heat the refrigerant in the refrigerant circuit. The bodymay comprise a number of integrated components. A fuel cell coupledrefrigeration system may be referred to herein as a heat drivenrefrigeration system. Heat transfer devices may be liquid-to-liquid,gas-to-gas, surface-to-liquid and surface to gas heat transfer devices.Air is an exemplary gas.

As used herein, the term “evaporator” is a component that is thermallycoupled, directly or indirectly, to a thermal load to remove heattherefrom.

The foregoing embodiments and additional embodiments of the disclosurewill now be described with reference to the figures. Referring to FIG.1A, a general embodiment of a fuel cell coupled refrigeration system 25for use in the integrated energy management system according to thedisclosure includes a heat driven refrigeration system 50 thermallycoupled to a thermal load 52 and to a fuel cell 60, and a fuel cell fuelsupply 64. Excess heat from fuel cell 60 is applied, via heat exchanger(i.e., generator as shown in FIG. 1A) 72, to increase the temperature ofa refrigerant (not shown) flowing in refrigeration system 50 and atleast partially increases the pressure of the refrigerant. Refrigerationsystem 50 provides or removes thermal energy to or from thermal load 52to heat or cool thermal load 52.

As shown in FIG. 1B, generally, an integrated energy management system10 includes fuel cell coupled refrigeration system 25, and mayadditionally include an additional energy source 30, an electricalenergy storage device 34, a power circuit 40, an energy managementsystem 44, and an electrical load 54. Energy source 30 provides energythrough power circuit 40 to one or both of refrigeration system 50 andelectrical load 54. Exemplary additional energy sources includemechanical, direct current (DC) and alternating current (AC) energysources. Exemplary mechanical power sources include belts and gearsdriven by engines, hydraulic turbines and other non-electrical sourcesof energy. Exemplary AC energy sources include generators and an ACpower grid. Exemplary DC energy sources include energy storage devices,fuel cells and solar arrays.

In one embodiment, fuel cell coupled refrigeration system 25 of theintegrated energy management system 10 is comprised in a building.Energy source 30 comprises an electrical power grid (not shown)providing AC power to refrigeration system 50, in this case avapor-compression refrigeration system, through power circuit 40. Energymanagement system 44 monitors thermal load 52 of refrigeration system 50and forecasts the power requirements of refrigeration system 50 byapplication of known thermodynamic and energy balance principlesinvolving temperature differential, mass and fluid flow parameters. Theforecast may be based, for example, on historical trends, externalambient temperature measurements and operating profiles. An exemplaryprofile includes an ambient temperature setpoint and a demand formulabased on the ambient temperature setpoint and an actual temperature.Energy management system 44 determines how much electrical energy andheat to produce with fuel cell 60 based on the forecast, a profile, andthe availability of AC energy from the power grid.

In one example, power circuit 40 includes an inverter device, orinverter (not shown). In one variation, energy management system 44incorporates a fuel cell control system such as fuel cell managementsystem (FMS) 140 described with reference to FIGS. 10 and 11.

In another variation, energy management system 44 determines, based on acost threshold of electrical energy supplied by the power grid, whetherit is economical to sell electrical energy back to the power grid and,if so, operates power circuit 40 to transfer electrical energy generatedby fuel cell 60 to the power grid.

In one example, the cost threshold is the peak power cost of theelectrical energy supplied by the power grid. In another example, thecost threshold is a predetermined difference between the energy cost ofthe power grid energy and the fuel cell supplied energy.

In a further variation, power circuit 40 includes an inverter (notshown) and energy management system 44 is operable, with power circuit40, to regulate power received from the power grid and thus manageopportunity costs. In one example, opportunity costs are managed byscheduling energy consumption. Generally, scheduling comprisescontrolling target temperatures and operating loads so as to minimizeconsumption during peak hours. The inverter provides a central DC bus.In one example, converters are provided to convert the DC voltage and ACvoltage from different power sources (e.g. solar arrays, fuel cells andAC generators) to a common DC bus voltage. Power management system 44 isconfigured to regulate current drawn from the DC bus voltage by therefrigeration system and the electrical loads. Based on the currentdraw, energy storage system charge level, and refrigeration parameters,energy management system 44 determines how much energy to draw from thepower grid.

In some embodiments, energy management system is similar to energymanagement system 178, described with reference to FIG. 11, andcomprises a processing device 242 and a memory device 244 having storedtherein an application 248, which when executed by the processing device242 causes energy management system 178 to control one or more of powercircuit (not shown), refrigeration system 150, 308, electrical load 104and fuel cell 100.

In one example, the memory device 244 includes a plurality of operatingprofiles for controlling power circuit, refrigeration system 150, 308,electrical load 104 and fuel cell system 100. Each profile is configuredto control operation of the devices in a particularized way such thatenergy management system 178 can change operation of the system 178 byselecting a different operational profile. Further, fuel cell coupledrefrigeration system 300 may be configured with different modes ofoperation which may be comprised in a single profile or embodied indifferent profiles.

In one embodiment of multi-mode operations, a profile has a first and asecond mode of operation and energy management system 178 switchesbetween the first and second modes depending on predeterminedconditions. In a cost-saving mode of operation, electrical energyproduced by fuel cell 100 is converted to AC energy and supplied,together with AC energy from the power grid, to refrigeration system150, 308. Fuel supplied by fuel cell fuel supply 105 is consumed by fuelcell 100 to produce electrical energy, which is consumed byrefrigeration system 150, 308, and excess heat. The excess heat isapplied to refrigeration system 150, 308 to reduce consumption ofelectrical energy by refrigeration system 150, 308. Exemplary fuelsinclude natural gas and propane gas. Thus, operation of fuel cell 100reduces consumption of electrical energy from the electrical power gridwhile consuming fuel cell fuel. The cost-saving mode of operation ismost economical during periods of time during which the cost of energyreceived from the power grid is higher than the cost of energy obtainedfrom conversion of fuel by the fuel cell.

In another cost-saving mode of operation, referring back to FIG. 1B,energy management system 44 is configured to control operation ofelectrical load 54. In one variation, energy management system 44energizes electrical load 54 during periods of time in which the cost ofenergy from the power grid is not at a maximum. In another variation,energy management system 44 energizes electrical load 54 during periodsof time in which refrigeration system 50 is not operating to reduce apeak-demand from the power grid. In a further variation, energymanagement system 44 energizes electrical load 54 with energy stored inelectrical energy storage device 34. In one example thereof, energymanagement system 44 energizes electrical load 54 with energy stored inelectrical energy storage device 34 during periods of time in which thecost of energy from the power grid is at a maximum. In another examplethereof, energy management system 44 energizes electrical load 54 withenergy stored in electrical energy storage device 34 is above a chargethreshold. An exemplary profile for a grid power supplied systemincludes a relationship between electricity prices and demand levels andtime of day. In one further example, the demand levels comprise a demandforecast.

In a reliability mode of operation, electrical energy produced by fuelcell 60 is supplied to refrigeration system 50 to operate refrigerationsystem 50 even if power from energy source 30 is unavailable. The DCenergy from fuel cell 60 is inverted into AC energy and the AC energy issupplied to refrigeration system 50. In another example, energy source30 supplements the DC energy supplied from fuel cell 60 to operaterefrigeration system 50.

In yet another example, fuel cell coupled refrigeration system 25 iscomprised in an electric vehicle and energy source 30 comprises amechanical energy source driving the compressor of a vapor-compressionrefrigeration system. In a further example, fuel cell coupledrefrigeration system 25 is comprised in an electric vehicle andrefrigeration system 50 comprises an absorption or ejectionrefrigeration system.

In a further variation of the present embodiment, a first mode ofoperation causes energy storage device 34 to maintain a substantiallyfull charge while a second mode causes energy storage device 34 tosubstantially deplete its charge. Thus, in the second mode energystorage device 34 is a net provider of electrical energy. When selected,the profile enables the system to charge in the first mode and toprovide energy to the power grid in the second mode. In anothervariation, the profile is configured to operate the refrigeration system50 primarily from energy source 30 when the cost of energy source 30 islow and to operate fuel cell 60 when the cost of energy from energysource 30 is high. The profile includes values for low and high costthresholds. In a further variation, a profile includes operatingschedules which enable electrical load 54 to be operated during lowpower grid cost periods. In a yet further variation, a profile causesrefrigeration system 50 to maintain a target refrigeration parameter,e.g. temperature and/or temperature variation, near a limit of a rangewhen it is economical to do so and near the opposite limit otherwise.For example, the profile may be defined to cool a target space to thelow temperature limit of the range when grid energy costs are low and tooperate near the upper temperature limit when grid energy costs arehigh. Thus, the refrigeration system 50 operates more during low costperiods than during high cost periods. Furthermore, the profile maycause energy storage device 34 to charge during the low cost period anddischarge during the high cost period after the target space approachesthe high temperature limit. The profile is selected from a plurality ofprofiles manually or automatically. In one variation, the user selects anew profile with a user input device (not shown). For example, a usermay choose a profile to draw energy primarily from fuel cell 60 andenergy storage device 34 if energy source 30 becomes unreliable even ifthe profile does not result in the most economical consumption. The usermay then switch to a profile selected for economy when reliability ofenergy source 30 increases. Similarly, in a mobile application, the usermay choose profiles based on anticipated traffic or terrain choices,choosing between profiles optimized for performance, economy,reliability or other characteristics.

In another variation, the profiles are conditioned such that asoperating or ambient variables change, the energy management system 44automatically selects a new profile. In one example, the energymanagement system 44 selects a reliability profile after it detectsintermittent or unreliable supply from the power grid. In anotherembodiment, the energy management system 44 changes profile if, while inan economy mode, it is unable to satisfy the refrigeration target.Similarly, in a mobile application example, the energy management system44 automatically changes from economy to performance profiles (or modes)if it is unable to reach performance targets with the economy profile(or mode).

In another variation of the present embodiment, electrical load 54comprises a thermal heating device (not shown) thermally coupled withrefrigeration system 50. Energy management system 44 cycles fuel cell 60and the thermal heating device to heat the refrigerant alternativelywith excess heat from fuel cell 60 and the thermal heater. In oneembodiment, the thermal heating device is an electric heating device.One skilled in the art, however, would easily recognize that any thermalheating device as known in the art can be used as the thermal heatingdevice without departing from the present disclosure.

Fuel cell coupled refrigeration system 25 may be comprised in a buildingor a mobile application. A fuel cell coupled refrigeration system suchas fuel cell coupled refrigeration system 25 may be comprised in anelectric vehicle to provide range extension or comfort features asdisclosed with reference to FIGS. 12-13.

A method to operate an integrated energy management system is alsoprovided herein. In one embodiment, the method comprises generatingelectric energy and thermal energy with a fuel cell; storing at least aportion of the electric energy in an energy storage device; and drivinga refrigeration cycle of a refrigeration system, at least sometimes,with energy provided by a first source of energy and with thermal energyfrom the fuel cell.

In one variation, the method further comprises changing an energy ratiobetween the energy provided by the first source of energy and thethermal energy responsive to a variable associated with the first sourceof energy. By changing the energy ratio, for example by increasing fuelcell energy production and reducing supply from the first sourceaccordingly, or vice-versa, the overall energy cost consumed by the fuelcell coupled refrigeration system can be adjusted. As the cost of energyfrom the first source and the fuel cell vary, due to fluctuations inpricing or efficiency, for example, the energy ratio is adjustedaccordingly to minimize cost relative to what cost would be if the ratioremained unchanged. In one example, the variable is the energy cost ofthe energy from the first source of energy, and the changing comprisesreducing the energy ratio when the energy cost of the energy from thefirst source of energy increases. In another example, the variable isthe energy cost of the energy from the first source of energy, and thechanging comprises reducing the energy ratio when the energy cost of theenergy from the first source of energy exceeds a predetermined high costlevel. In a further example, the first source of energy is the energystorage device and the changing comprises reducing the energy ratio whena charge level of the energy storage device reaches a predetermined lowcharge level.

The present integrated energy management system is applicable instationary and mobile applications. In one variation, the method furthercomprises operating a vehicle including a propulsion system, anintegrated energy management system including the refrigeration systemand the fuel cell, and changing, by the integrated energy managementsystem, an energy ratio between the energy provided by the first sourceof energy and the thermal energy responsive to a variable associatedwith the first source of energy. In another variation, the methodfurther comprises operating the refrigeration system and the fuel cellwith an integrated energy management system to control a buildingtemperature, and changing, by the integrated energy management system,an energy ratio between the energy provided by the first source ofenergy and the thermal energy responsive to a variable associated withthe first source of energy.

The present integrated energy management system is also applicable, instationary applications, to manage interaction with a power grid. In onevariation, the first source of energy is an electrical power grid, andthe method further comprises, by the integrated energy managementsystem, reducing the ratio when an energy cost of the electrical energyfrom the electrical power grid exceeds a predetermined kilowatt-hourcost. In another variation, described in more detail below, the ratio isincreased and excess power can then be sold to the power grid.

In another embodiment, the method comprises generating electric energyand thermal energy with a fuel cell; driving a refrigeration cycle of arefrigeration system, at least sometimes, with energy provided by apower grid and with thermal energy from the fuel cell; and, at othertimes, providing energy generated by the fuel cell to the power grid.

The integrated energy management system of the present disclosure isalso applicable, in stationary applications, to manage interaction witha power grid. In one variation, the first source of energy is anelectrical power grid, and the method further comprises, by theintegrated energy management system, reducing the ratio when an energycost of the electrical energy from the electrical power grid exceeds apredetermined kilowatt-hour cost. In another variation, described inmore detail below, the ratio is increased and excess power can then besold to the power grid.

The embodiments described herein above and below are illustrative.Additional embodiments include any combination of the variations andexamples provided herein. Furthermore, while the energy control conceptshave been described with reference to a refrigeration system, theconcepts are also applicable to systems in which thermal energy fromfuel cells may be used to substitute other forms of energy. Moreparticularly, heat from a fuel cell is provided to an appliance toreduce consumption of electrical or gas energy. In one example, theappliance is a water heater. A heat exchanger is coupled to the waterheater. When the fuel cell operates, heat from the fuel cell istransferred to the water in the water heater, directly or indirectly, bythe heat exchanger. An exemplary integrated energy management systemincludes a fluid conduit fluidly coupling the fuel cell and the waterheater. In one example, a water heater system is retrofitted byinserting a heat exchange loop in the existing hot water or water heaterpiping. Water is circulated through, and heated in, the heat exchangeloop.

In another example, a heat exchange loop is physically coupled to thewater heater to heat the water indirectly such that the heated waterdoes not contact the heat exchange loop. In one embodiment of acost-saving method, the integrated energy management system determinesuse and non-use periods based on historical trends or via userprogramming. The integrated energy management system controls the watertemperature setpoint and prevents the water heater from heating waterduring non-use periods. Instead, the integrated energy management systemdirects fuel cell heat to the water heater to raise the watertemperature to the target temperature just prior to the use period.Exemplary water heaters include electric and gas water heaters.

In another embodiment of a cost-saving method, the integrated energymanagement system directs grid supplied energy to an electric waterheater to raise the water temperature to the target temperature justprior to the use period so long as the heating period coincides with atime when grid power is below a predetermined cost threshold. Otherwise,the integrated energy management system directs grid supplied energy tothe water heater to raise the water temperature to the targettemperature just prior to the time when grid power is above thepredetermined cost threshold. In a further embodiment of a cost-savingmethod, the integrated energy management system reads an on/off statusof electrical or thermal loads and adapts operation of the fuel cellaccordingly.

The variations and examples provided above are also applicable to otherthermal and electrical loads including, for example, dishwashers,clothes washers and dryers, and other household appliances. In a furthervariation, the integrated energy management system operates theappliances and the fuel cell to reduce charging and discharging cyclesof the energy storage device.

Typically the fuel cell coupled refrigeration systems used in theintegrated energy management systems of the present disclosure includeheat driven refrigeration systems including absorption refrigeration andejector refrigeration systems. Absorption refrigeration relies on theuse of a liquid media (the “adsorbent”) such as water or lithium bromidethat is capable of adsorbing a large amount of a refrigerant at lowtemperature and pressure. The refrigerant, for example ammonia, sulfurdioxide, water or a hydrocarbon as known in the art, passes through acondenser, an expansion valve and an evaporator in the same way as inthe vapor-compression system described above. The compressor is replacedby an adsorber, a pump and a generator. As the refrigerant passesthrough the adsorber, it is adsorbed by the adsorbent and heat isreleased to the environment. The refrigerant and the adsorbent thenenter a pump where the pressure of the mixture increases to thegenerator's pressure. The mixture is heated in the generator to separatethe high-pressure refrigerant from the adsorbent.

Ejector refrigeration is a refrigeration cycle that also relies on heatinput rather than mechanical means to drive the cycle. The ejectorrefrigeration system consists of two loops, the refrigeration loop andthe power loop. In the power loop, the liquid refrigerant is pumped intoa generator where an external heat source (e.g., fuel cell and/orelectric heating device) vaporizes the refrigerant resulting in highpressure vapor called the primary fluid. The primary fluid expandsthrough the ejector's nozzle and increases its velocity. This creates avacuum in the refrigeration loop which draws in the vapor from theevaporator called the secondary fluid. The secondary fluid enters theejector's diffuser where the velocity decreases and the pressurerecovers. The secondary fluid goes through a condenser where heat isrejected to the environment. The condensed liquid is partly pumped backto the generator completing the power loop. The remaining condensedliquid is drawn into an expansion valve where the pressure is lowered.The liquid enters the evaporator where the low pressure created by theprimary fluid allows the secondary fluid to evaporate at very lowtemperature and thereby provide the cooling effect. The secondary fluidthen enters the ejector completing the refrigeration cycle.

In another embodiment, a fuel cell coupled refrigeration system coupledto an energy management system is provided. In the present embodiment,the fuel cell coupled refrigeration system is also coupled to an energystorage system, forming an integrated energy management system accordingto one embodiment of the present disclosure. The energy storage systemgenerates heat as it charges. The amount of heat is related to thecharging and discharging rate of the energy storage system. The powergeneration efficiency of fuel cells, on the other hand, is inverselyrelated to power demand. Therefore, when the energy storage system isnearly fully discharged, charging generates a relatively large amount ofheat and causes the fuel cell charging the energy storage system tooperate inefficiently. At the same time, however, due to the highelectrical energy demanded by charging, the fuel cell generates a largeamount of heat. It has unexpectedly been found that as the fuel cellgenerates more power to charge the energy storage system, and thus,generates more heat, more effective cooling is generated by the fuelcell coupled refrigeration system. Advantageously, the cooling effect isgenerated at a time that it is most needed by the energy storage system.

In one variation, the energy management system prevents substantialdischarge of the energy storage system. In another variation, the energymanagement system cycles the fuel cell's electrical power production ata predetermined rate to maintain a desired charge level, and reduces thecycling rate when the heat load demand increases above a predeterminedheat demand level. Exemplary energy storage systems include energystorage devices such as batteries and capacitors. In a furthervariation, the energy storage system powers heating and cooling devicesunder low or no load conditions. In one example, the refrigerationsystem cools the energy storage devices. In another example, a heatingdevice powered by the energy storage device drives the refrigerationsystem under no or low load conditions.

In further embodiments, the foregoing integrated energy managementsystem is configured to extend the range of a vehicle and/or to providecomfort heating and cooling features. In even further embodiments, theforegoing integrated energy management system includes additionalheating and cooling components to transfer thermal energy, or heat, toand from thermal loads.

Referring to FIGS. 2-9, exemplary embodiments according to thedisclosure of integrated energy management systems including fuel cellcoupled refrigeration systems are provided. Referring to FIG. 2, in oneembodiment a fuel cell coupled refrigeration system 100 comprises anabsorption system 400 including a heat exchanger 152, such as anevaporator having a heat receiving surface 416, coupled to a thermalload 402, an adsorber 424, a pump 428, at least one generator 430, 432,a condenser 440 and an expansion valve 442. The system 100 alsocomprises an exemplary fuel cell system, illustratively fuel cell 410,thermally coupled to generators 430 and 432. Heat output by fuel cell410 provides thermal energy to generators 430 and 432 to drive therefrigeration cycle of absorption system 400 as described above.

In one embodiment, an electric heating device 220 drives therefrigeration cycle when fuel cell 410 does not generate sufficient heatto do so. An additional unexpected advantage of coupling the electricheating device 220 and fuel cell 410 is that this allows decoupling ofthe thermal and electrical loads from the fuel cell. That is, when aseparate electrical load provides electrical energy to electric heatingdevice 220, heat produced from electric heating device 220 combines withheat produced by fuel cell 410 to drive the refrigeration cycle. When noseparate electrical load is provided, however, electrical energyproduced by fuel cell 410 can drive electric heating device 220, whileheat produced from fuel cell 410 may still be used to drive therefrigeration cycle. It should be recognized that although describedherein as an electric heating device, any other heating device as knownin the refrigeration art can be used as a supplemental or alternativethermal energy source to the fuel cell for providing heat to drive therefrigeration cycle.

Generators 430 and 432 may be manufactured applying known heat exchangeprinciples based on contact surface and fluid flow control to maximizethe transfer of heat generated by fuel cell 410 to the fluid mixturecirculating through the generator to cause the mixture to separate intoits absorbent and refrigerant constituents. Another method of achievingheat transfer may be through boiling or phase change heat transfer inthe generator 430, 432. Heat is transferred by heat transfer surface 416from thermal load 402 and evaporated by the heat exchanger (evaporator)152 thereby cooling thermal load 402. In one example, thermal load 402is an electric vehicle battery compartment. In another example, thermalload 402 also includes a passenger cabin or compartment.

In one embodiment (not shown), fuel cell 410 also functions as a heatsource for a heat load in addition to heating generators 430 and 432. Aseparate heat exchanger may be used to extract heat from fuel cell 410for heating purposes. For example, in one embodiment, a dual purposeheat exchanger is provided configured with separate heat transferconduits. One conduit extracts heat for use with refrigeration system400 when refrigeration is required and another conduit extracts heat forheating of thermal load 402 when heating is required.

In one particularly suitable embodiment, the fuel cell comprises atleast one proton exchange membrane (PEM) fuel cell designed to convertfuel such as pure hydrogen or a hydrogen-rich gas stream and an oxidantsuch as air in an electrochemical reaction that generates water vapor,electrical power and waste heat. Each cell includes a PEM membranedisposed between bipolar plates. Fuel cells may operate at differenttemperatures. Low-temperature PEM fuel cells operate between 60° C. and80° C. High-temperature PEM fuel cells may operate between 95° C. and180° C. and reject heat at about 150° C. Typically, absorptionrefrigeration can be achieved with heat at a temperature of about 60° C.Similarly, thermal compression or isochoric compression of typical aircooling system refrigerants can be achieved with heat at a temperatureof about 60° C. The temperature differential between the rejected heatand the generator, which determines the heat transfer efficiency, alsodetermines the size of the exchange surface required to transfer heatfrom a typical PEM fuel cell to a generator. Thus, the size of thegenerator to exchange heat with a low-temperature PEM fuel cell is muchlarger than the size of a generator used with a high-temperature PEMfuel cell to achieve the same heat transfer rate. Furthermore, at thetemperatures at which the high-temperature PEM fuel cells operate, it ispossible to transfer enough heat to run a compact generator utilizingthe external surfaces of the fuel cells rather than having to circulatefluid through the bipolar plates. The ability to extract sufficient heatfrom the external surfaces simplifies and enables construction of anintegrated fuel cell/generator structure.

In another embodiment, however, heat exchange may be improved bycirculating fluid through the biopolar plates to increase the contactsurface. This configuration enables the use of low-temperature PEM fuelcells with fuel cell coupled refrigeration systems as described in thepresent disclosure.

In another example, a second cooling conduit is built into the generatorto construct a dual purpose generator. Independent flow control of theconduits permits the fuel cells to both heat a thermal load andrefrigerate a second thermal load with the refrigeration system. In onevariation, dual loop generators are used in stationary systems usinglead-acid batteries to store energy generated by the fuel cells. Becausetemperature control can extend the life of lead-acid batteries, heatingand cooling to maintain a desired temperature within a narrow band isdesirable and achievable with a dual purpose generator. In anothervariation, described with reference to FIG. 7, a dual loop generator isused in conjunction with an auxiliary cooling loop.

Referring to FIG. 3, in another embodiment, a fuel cell coupledrefrigeration system 100 is provided comprising an air pump or fan 456forcing air to flow through fuel cell 410. The forced air absorbs heatproduced by fuel cell 410 and transfers the heat to the environment orto a thermal load. For example, thermal load 454 is shown in FIG. 3receiving heat from the forced air.

In one embodiment, an integrated energy management system is configuredto control the temperature of one or more compartments (not shown). Whenheating is desired, the fuel cell coupled refrigeration system 100transfers heat from fuel cell 410 to the compartments.

In some embodiments, the fuel cell coupled refrigeration systems includeauxiliary cooling systems. Embodiments of fuel cell coupledrefrigeration systems including auxiliary cooling systems according tothe disclosure are described with reference to FIGS. 4 and 5. In FIG. 4,an auxiliary cooling system 446 includes a heat exchanger 444, aradiator 448 and a pump 452.

For example, in an electric vehicle application, pump 452 is powered byan energy storage system (not shown) which is in turn powered by fuelcell 410. A refrigerant is circulated in a cooling loop throughauxiliary cooling system 446 to cool, at least partially, fuel cell 410.In one embodiment, generator 430 and heat exchanger 444 are integratedin a dual purpose generator. In an alternative embodiment, separate heatexchange components are independently coupled to the fuel cell 410. Ifthe refrigeration system 100 is not in operation, auxiliary coolingsystem 446 cools fuel cell 410. If some refrigeration is desired,absorption refrigeration system 400 and auxiliary cooling system 446 maybe selectively operated by an energy management system to maximize theefficiency of the fuel cell coupled refrigeration system 100. In afurther embodiment, generator 430 also includes heating device 220.

In FIG. 5, an auxiliary cooling system 460 includes heat exchanger 444,radiator 448, pump 452, and a liquid cooled fuel cell 466 thermallycoupled to a second heat exchanger 464. A refrigerant is circulatedthrough cooling system 460 to cool fuel cell 466. The refrigerant may becirculated through fuel cells to draw heat from fluid channels disposedwithin the fuel cell bipolar plates or around their periphery. Heat isthen transferred from the refrigerant to generator 430 by heat exchanger444. Alternatively, heat is removed from the refrigerant by radiator448. In the arrangements described with reference to FIGS. 4 and 5, theauxiliary cooling system 446, 460 supplements fuel cell thermalmanagement utilizing a liquid refrigerant such as water, ethyleneglycol, propylene glycol or mineral oil. The auxiliary cooling system446, 460 provides operational flexibility by enabling fuel cell 410, 466to operate independently from the absorption refrigeration system 400,480. Auxiliary cooling is particularly useful when radiator 448 candischarge absorbed heat to a heat load (not shown).

Referring to FIG. 6, in another embodiment of a fuel cell coupledrefrigeration system for use with an integrated energy management systemaccording to the disclosure, an ejector refrigeration system 670 isprovided. Ejector refrigeration system 670 comprises a refrigerantreservoir 672, expansion valve 642, heat exchanger 652, a pump 674pumping refrigerant through the fuel cell coupled refrigeration system500, an ejector 676 having an ejector nozzle 680, and condenser 640. Thepower loop includes pump 628 to pump the refrigerant therethrough andfuel cell 610 thermally coupled to heat exchangers 678 and 679. Afterexiting the power loop, the refrigerant is mixed with secondary fluidexiting refrigeration system 670 and heat is removed therefrom.

In a variation thereof (not shown), an auxiliary cooling system isprovided as described with reference to FIGS. 4 and 5. During operation,refrigerant is pumped into the power loop from reservoir 672 to heatexchangers 678 and 679. The excess heat produced by fuel cell 610vaporizes the refrigerant which maintains the fuel cell temperaturewithin an optimal range, for example, at temperatures of from about 120°C. to about 150° C. The vaporized refrigerant enters ejector nozzle 680at high pressure and is throttled to high velocity. This increase invelocity draws the secondary fluid in the refrigerant loop into ejector676. The same refrigerant used as the primary fluid is also used for thesecondary fluid. The secondary fluid first enters expansion valve 642which opens only if below a certain pressure, for example below about 8and 10 mbar absolute. The refrigerant flows into evaporator 652 and pump674 before entering ejector 676. Pump 674 is added to achieve a deepervacuum thereby causing the refrigerant to boil at lower temperature. Inone embodiment, the refrigerant is water and the boiling point of thewater is decreased to between 50° C. and 80° C. The fluid mixtureexiting from ejector 676 is routed to condenser 640 which rejects theheat picked up by the refrigerant to the atmosphere. The refrigerantthen returns to reservoir 672.

In one variation, electric heating device 700 is provided as analternative/supplemental heat source to drive the refrigeration cycle ofejector refrigeration system 670. In one example, heating device 700 andfuel cell 610 are cycled to alternatively drive the refrigeration cycle,at least sometimes. In another example, heating device 700 and fuel cell610 are operated concurrently, at least sometimes, to drive therefrigeration cycle. It should be recognized that by having the electricheating device 700, the fuel cell power output and heat generation canbe decoupled from the heating load and the electrical load as describedabove, enabling greater operational flexibility.

In other embodiments of an integrated energy management system includinga fuel cell coupled refrigeration system, as shown in FIG. 7, therefrigeration system 300 comprises a compressor 310. The compressor 310may be powered by electrical energy (e.g., alternating or directcurrent) (not shown). In one embodiment, compressor 310 may be poweredby electrical energy generated by fuel cell 314. In one variation, Q₁,such as is provided by fuel cell 314, is used to induce isochoriccompression of the refrigerant to reduce an energy requirement of thecompressor 310. In one embodiment, the system 300 is operable toincrease a pressure of a portion of the refrigerant downstream of thecompressor. In a form thereof, the pressure is increased by heating theportion of the refrigerant in a substantially constrained volume. Byheating in a substantially constrained volume, pressure increases. Inanother embodiment, heating can also be applied in a not-substantiallyconstrained volume so long as heating increases the pressure of therefrigerant, for example by controlling feed and discharge flow ratessuch that the pressure is not relieved as a result of decreased flow.

In yet another embodiment, the pressure is increased by expanding steam(not shown) generated by fuel cell 314 to compress the refrigerant. Asthe steam increases in a constrained space, the refrigerant iscompressed and its pressure increases. Increasing the pressure reducesan energy requirement of compressor 310. Thus, for the same amount ofheating or cooling demanded of refrigeration system 300, less electricalenergy 312 is consumed as a result of the application of thermal energyfrom fuel cell 314 to refrigeration system 300. In one embodiment, fuelcell 314 is operated between 60° C. and 180° C. More particularly, inone embodiment, a low temperature PEM fuel cell is operated between 60°C. and 80° C. In another embodiment, an intermediate temperature PEMfuel cell is operated between 90° C. and 150° C. In yet anotherembodiment, a high temperature PEM fuel cell is operated between 100° C.and 180° C.

In one suitable embodiment, a method according to the disclosureincludes retrofitting a vapor-compression refrigeration system, such assystem 300, by adding generator 316 and fuel cell 314 to transfer excessheat from the fuel cell 314 to the refrigerant.

Referring to FIGS. 8 and 9, exemplary embodiments of a fuel cell coupledvapor-compression refrigeration system 1000 for use with an integratedenergy management system according to the disclosure are provided. Fuelcell coupled refrigeration system 1000 includes vapor-compressionrefrigeration system 480 coupled to a generator 430 to heat therefrigerant. As shown in FIG. 8, generator 430 is coupled upstream of acompressor 482, between compressor 482 and condenser 440. In anothervariation, generator 430 is coupled downstream of compressor 482. Forexample, generator 430 may be coupled downstream of compressor 482between heat exchanger 152 and compressor 482. As illustrated in FIGS. 8and 9, vapor-compression refrigeration system 480 comprises,respectively, auxiliary cooling systems 446 and 460. In a furthervariation, system 480 does not include an auxiliary cooling system. Inall of the above variations and examples, generator 482 compresses therefrigerant, and generator 430 raises the temperature of the refrigerantsuch that the energy consumed by compressor 482 is reduced whengenerator 430 operates relative to when it does not.

As noted above, alternative/supplemental energy sources may be includedin the fuel cell coupled refrigeration systems. Referring to FIG. 10, aschematic diagram of an integrated energy management system including afuel cell coupled refrigeration system according to an embodiment of thedisclosure, including a fuel cell system 100, a heat drivenrefrigeration system 150, and a battery system 160, is provided to powera load 104. Fuel cell system 100 includes a fuel cell 110, a fuel cellmanagement system (FMS) 140, and a fuel reservoir 130 containing fuelfor the fuel cell 110. In the present embodiment, fuel cell system 100includes a fluid conduit 120 thermally coupled to fuel cell 110 toextract heat therefrom and having an inlet 122 and a discharge outlet124. When fuel cell system 100 operates, the fluid passing through fluidconduit 120 is heated and the heated fluid then flows to refrigerationsystem 150. In a variation thereof, a heat exchanger 152 (e.g.,generator) of refrigeration system 150 is physically and thermallycoupled to fuel cell system 100 to extract heat from surfaces of fuelcell 110. FMS 140 is communicatively coupled by a signal line 191 to anenergy management system 178 and receives a demand signal therethrough.The demand signal causes FMS 140 to control fuel cell system 100 toprovide fuel to fuel cell 110 in relation to the amount of energyrequired by energy management system 178 to enable an electrochemicalreaction in fuel cell 110. Electrical power produced by theelectrochemical reaction is provided via power lines 171 and 172 tobattery system 160. FMS 140 includes a power conditioner (not shown)which converts the voltage of electrical energy generated by fuel cell110 to a voltage compatible with battery system 160. Electrical power isprovided via power lines 173 and 174 from battery system 160 to load104. Exemplary loads include propulsion systems in mobile applications,computing systems of telecommunication systems or mobile systems, andany other compatible electrical system.

In particularly suitable embodiments, fuel cell 110 is electricallycoupled in parallel with battery cell stack 162 and load 104. In thisconfiguration, fuel cell 110 can participate in powering the electricalload 104 in conjunction with battery system 160. In cases where load 104is lower than fuel cell 110 power output, fuel cell 110 can rechargebattery cell stack 162 while providing power to load 104.

In the present embodiment, heat exchanger 152 is configured to receiveheat from battery system 160. Refrigeration system 150 further includesa fluid supply line 154 fluidly coupled to inlet 122 and a fluid returnline 156 fluidly coupled to discharge outlet 124. A primary fluidcirculates through refrigeration system 150, fluid supply line 152,fluid conduit 120 and fluid return line 156 driven by a fluid pump (notshown) or by density changes caused by temperature variations in therefrigerant. As the primary fluid passes through fluid conduit 120 itreceives heat from fuel cell 110 and then refrigeration system 150discharges the heat to the environment or to a heat load. The heatreceived by refrigeration system 150 drives its cooling cycle asexplained above and below with reference to FIGS. 2-9. Refrigerationsystem 150 also extracts heat from battery system 160 with heatexchanger 152. In one variation of the present embodiment, fluid conduit120 is comprised by a generator (not shown), and the generator isintegrated with fuel cell 110. While the fuel cell coupled refrigerationsystem depicted in FIG. 10 has been described with reference to abattery system, the invention is not so limited. In one variation of thefuel cell coupled system with an additional energy source as depicted inFIG. 10, the system comprises any electrical energy storage device.

In another variation of the present embodiment, the primary fluid isthermally coupled to an electric heating device 200 having a fluidconduit 203 between an inlet 202 and a discharge outlet 204. In oneexample, heating device 200 comprises a plurality of electric heatingbands 206 configured to heat fluid conduit 203 and fluid passingtherethrough. Heating device 200 is powered by power lines 175 and 176which are supplied power by battery cell stack 162 of battery system 160or directly by the fuel cell. A switching device 210 is controlled byenergy management system 178 with a control signal supplied via a signalline 192 to engage or disengage heating device 200. Exemplary switchingdevices include relays and contactors.

As explained further below with reference to FIGS. 11 and 12, accordingto various embodiments disclosed herein it is advantageous to enableoperation of refrigeration system 150 even when fuel cell system 100 isnot producing electric power. At such times, battery system 160 powersheating device 200 to produce sufficient heat to drive the refrigerationcycle. When the charge level of battery system 160 is sufficientlyreduced, e.g. below a no-load charge threshold, energy management system178 engages fuel cell system 100 to recharge battery system 160, therebyalso producing sufficient heat to drive the refrigeration cycle, anddisengages heating device 200. In one example, energy management system178 engages fuel cell system 100 when its charge level is below 90%. Inanother example, energy management system 178 engages fuel cell system100 when its charge level is below 80%. The no-load charge threshold isa design choice dependant on the sizes and response times of theintegrated energy management system components.

The no-load charge threshold can depend on application specificvariables. Thus, multiple conditional no load charge thresholds may beapplicable under varying conditions. In one example, after the batteriesare sufficiently charged the fuel cell system is disengaged and theheating device is engaged to keep the refrigeration system working, tocool the batteries for example. Once the batteries reach a no-loadcharge threshold, the fuel cell system re-engages to charge thebatteries, the heating device disengages, and the fuel cell heat drivesthe refrigeration cycle. The fuel cell system and the heating device maycycle on and off as described herein for other purposes as well.

Battery system 160 includes a battery cell stack 162 and a batterymanagement system (BMS) 166. Battery management system 166 communicatesvia a demand signal on signal line 181, providing sufficient informationto enable energy management system 178 to engage fuel cell 100 at anappropriate power level to charge battery cell stack 162. In onevariation, BMS 166 determines, based on historical data and presentvoltage, a required charge rate and communicates the required chargerate and voltage to energy management system 178 via the demand signal.In another variation, energy management system 178 determines the chargerate based on a voltage signal on demand line 181. In a furthervariation, energy management system 178 determines the charge rate basedon a voltage signal on demand line 181 and predictive informationreceived on signal line 182 or any other signal lines as describedbelow. Based on the required charge information, FMS 140 calculates howmuch current is required given the voltage output by fuel cell 110 andconverts the voltage output to substantially match the present voltageof battery cell stack 162. FMS 140 adapts the DC/DC conversion ratio asthe present voltage increases during charging. BMS 166 may include apre-charge circuit suitable to receive electric energy from an externalsource. The functionality of the system has been described withreference to FMS 140, BMS 166 and energy management system 178 forsimplicity, but the present disclosure is not to be construed asrequiring three control components. The same functionality can beachieved with a single control component or with a distributed controlsystem in which the control logic is even more distributed than in thedisclosed embodiment. The control logic can be embodied in software, inhardware and in a hybrid system comprising software and hardware. Demandand control lines are described in singular form for simplicity. Demandand control lines may comprise one or more conductors transmitting oneor more signals each. In one example, demand and/or control linescomprise serial communication lines communicating a variety of datatypes such as data representative of voltage, current, timing, faultsand errors. In another example, demand and/or control lines comprisecontrol voltages or currents, for example 0-10 volts or 4-20 milliamps,as is know in the art of control systems. The control logic may also beintegrated with a control device controlling the overall operation of amobile or stationary system coupled to the integrated energy managementsystem.

In a further embodiment, the integrated energy management system iscomprised in an electric vehicle. The electric vehicle comprises anelectric propulsion system and the integrated energy management system.Exemplary propulsion systems comprise wheels or propellers driven by oneor more electric motors. Exemplary motors include regenerating motors.The integrated energy management system includes a fuel cell coupledrefrigeration system, such as shown in FIG. 10, to provide electricpower to the propulsion system. In one variation, the refrigerationsystem is coupled to a thermal load of the electric vehicle and theintegrated energy management system includes a comfort cycling feature.Accordingly, when the vehicle is parked, the fuel cell refrigerationsystem of the integrated energy management cycles to provide comfort. Inone example, comfort is provided by heating an electric vehicle cabinwhile the propulsion system of the electric vehicle is disengaged.Heating may be provided by the fuel cells or by an auxiliary heatingdevice powered by an energy storage system. In one example, heating isprovided by the fuel cells and the no-load threshold is set below acooling no-load threshold to enable the fuel cells to generate more heatthan would be generated if an optimal efficiency threshold were chosen.In another example, comfort is provided by cooling the electric vehiclecabin while the propulsion system of the electric vehicle is disengaged.When the electric vehicle is parked, the heating device and the fuelcell coupled refrigeration system cycle and the refrigeration systemcools the cabin.

An embodiment of an integrated energy management system including fuelcell coupled refrigeration system as in FIG. 10 in a mobile applicationis depicted in FIGS. 11 and 12. Referring to FIG. 11, an exemplaryschematic diagram of an electric vehicle 300 with an energy managementsystem 178 is shown comprising a plurality of heating sources and aplurality of cooling sources powered by fuel cell system 100, batterysystem 160 and refrigeration system 150. Some heating and coolingsources may be available, for example, if a vehicle is retrofitted witha fuel cell coupled refrigeration system. Battery system 160 is locatedin a battery compartment 304. An auxiliary heating source, denoted asheating device 306, is provided for heating a cabin 302 where a driverand passengers may be seated. Auxiliary cooling sources includeauxiliary fuel cell cooling system 310 and compressor refrigerationsystem 308. Sensors 250-257 comprise temperature sensors T1 T3designated to measure ambient temperature and the temperatures ofbattery system 160 and cabin 302. Sensors 253 and 254 comprise voltagesensors V1 and V2 designated to measure the output voltage of fuel cellsystem 100 and the voltage of battery system 160. Sensors 255-257comprise current sensors A1-A3 designated to measure the current outputby fuel cell system 100 and drawn by battery system 100 and load 104.Additional sensors may be provided to measure performance of auxiliaryheating and cooling components. Alternatively, each auxiliary heatingand cooling component may comprise an independent controllercommunicatively coupled with energy management system 178. Labels Q1-Q10represent heat, i.e. energy measured in calories or British ThermalUnits (BTU's), flowing through the electric vehicle. Q1 and Q6 representheat provided to cabin 302 and battery compartment 304. Q4 and Q5represent heat extracted from cabin 302 and battery compartment 304. Q2and Q10 represent heat provided to heat driven refrigeration system 150.Q7-Q9 represent heat vented to the environment. Of course, heat Q7-Q9can also be re-circulated to cabin 302 or battery compartment 304.Additional power lines may be required to power fluid circulation pumpsassociated with heat exchangers and refrigeration systems. In additionto sensors, energy management system 178 receives a plurality of signalson lines 181-184 and outputs a plurality of signals on lines 191-196.

Energy management system 178 further comprises a processing device 242,a memory device 244, and imbedded in memory device 244, an application248 including a plurality of processing instructions executable byprocessing device 242 to engage and disengage the heating and coolingsources, the integrated energy management system and other components ofelectric vehicle 300. Referring to FIG. 12, in one embodiment, controlsignals are provided on lines 191-196 to engage the integrated energymanagement system components and the auxiliary heating and coolingcomponents. As described above, the lines can comprise single andmulti-conductor lines which transmit simple demand signals or establishserial or other communication protocols to exchange information with thecomponents. In other words, control signals can be bi-directional so asto transmit control and programming data, e.g. temperature setpoint oron/off control signals, and receive performance data, e.g. temperature,volts, current, faults and any other feedback data. Furthermore,predictive input signals are provided on line 182 corresponding to aspeed control of electric vehicle 300, on line 183 corresponding to acomfort control, and on line 184 corresponding to a heating/cooling(H/C) demand. As explained with reference to FIGS. 13-15, predictivesignals may be utilized to provide range increasing and comfortfeatures.

Unless otherwise expressly stated in connection with a specific usethereof, the term “memory device” includes any variation of electroniccircuits in which processing instructions executable by a processingdevice may be embedded unless otherwise expressly stated in connectionwith the specific use of the term. For example, a memory device includesread only memory, random access memory, a field programmable gate array,a hard-drive, a disk, flash memory, and any combinations thereof,whether physically or electronically coupled. Similarly, a processingdevice includes, for example, a central processing unit, a mathprocessing unit, a video processing unit, a plurality of processors on acommon integrated circuit, and a plurality of processors operating inconcert, whether physically or electronically coupled. Furthermore andin a similar manner, in the context of a processing device, the term“application” includes a single application, a plurality ofapplications, one or more programs or subroutines, software, firmware,and any variations thereof suitable to execute instruction sequenceswith a processing device.

As described above, an integrated energy management system in a mobileapplication may be enhanced with predictive range extension and/orcomfort features. In one embodiment according to the disclosure, aplurality of profiles is obtained corresponding to a plurality of modesof operation. In one example, the integrated energy management systemincludes an algorithm programmed to operate so as to optimize particularprofiles. Referring to FIG. 12, a graph 500 of an output profilecorresponding to an electric vehicle operating in a “passing mode” isprovided. A curve 510 represents a speed demand signal includingsubstantially constant portions 511 and 513, and a constant but higherspeed portion 512 representing a desired passing speed. Curve 510 isshown for illustrative purposes as a square shaped curve. A passing modeprofile would naturally include some curvature representing a desireddegree of acceleration/deceleration between portions 511, 513 and 512. Acurve 520 represents the fuel cell system output. Curve 520 includes aconstant portion 523 and a curved portion 534. A line 522 is shown abovecurve 520 indicating the maximum output of the fuel cell, which is alsothe most inefficient output level. In a range extension mode, the fuelcell operates more efficiently and the range of the electric vehicle isthereby extended by preventing operation at the maximum output. A curve530 represents battery charge or voltage level. A line 532 is shownbelow curve 530 indicating the discharge threshold at which the batterysystem can no longer contribute a meaningful amount of power to powerthe vehicle. Before the battery system reaches this level, the fuel cellengages and the electric vehicle is powered, if necessary, by the fuelcell. If acceleration or high speed demand exceeds the capacity of thefuel cell, the electric vehicle will not respond to the driver'scontrols. Portion 533 of curve 530 represents a battery system voltageat constant speed. Since the voltage is constant, the fuel cell ispowering the electric vehicle. When the speed demand increases, theintegrated energy management system has two options: increase fuel celloutput or supplement its output with battery power. The latter option isrepresented by graph 500. Portion 534 shows a decrease in batteryvoltage as a result of batteries outputting power. However, if option 2continues for too long and into portion 535, the batteries will bedepleted which is a situation that should be avoided. Therefore, theintegrated energy management system increases the fuel cell output,indicated by portion 534, before the batteries become depleted tostabilize their voltage, as indicated by portion 536. Once speed demanddecreases, the fuel cell output is maintained for a while longer toenable the batteries to recharge, as indicated by portion 537. The rangeextension benefit results from the ability to use the batteries torespond to an increase in demand to reduce the fuel cell power levelincrease required to satisfy demand. The length of portion 512 fordifferent types of vehicles may be predicted based on electric vehicleusage history. If the battery voltage does not stabilize within apredefined time range, indicating that the predicted high speed portion512 has been exceeded, the fuel cell output may be increased to maximum.

Referring to FIG. 13, an output profile corresponding to an electricvehicle operating in a comfort mode is provided. A pre-start comfortwarm-up profile is illustrated by graph 600. A dashed line indicates thebattery voltage and a solid line represents the fuel cell output. Duringportions 622 the fuel cell does not output power and during portions 624the fuel cell does output power. During portion 612, the battery voltageis below its maximum level and the fuel cell does not output power,indicating that the electric vehicle is in a dormant state. At somepre-start time prior to a start up time, the fuel cell begins to chargethe batteries, which is represented by portions 624 and 614. Then, thefuel cell and a heating device cycle on and off to heat the cabin.During portion 616 the battery discharges as it powers the heatingdevice. In one example, the pre-start time is predicted based on asequence of start-up times detected over time. In another example, thepre-start time is indicated by a user. In another embodiment, the fuelcell and a refrigeration heating device alternatively cycle on and offto drive the refrigeration cycle and cool the cabin. Cooling may beginat a pre-start time as in the foregoing comfort heating cycling process.

Referring to FIG. 14, a short-stop comfort mode of operation isillustrated by graph 700. As indicated by portions 720 and 722, a loadcurrent is initially constant indicating that the electric vehicle isoperating at a constant speed, and then decreases, indicating that theelectric vehicle is slowing down and eventually stopping. Portions 740and 760 indicate that while speed is constant, the fuel cell isproviding propulsion power and the battery voltage is constant. When theelectric vehicle slows down, the fuel cell decreases power output, atportion 742, while the battery voltage increases, at portion 762,indicating that the fuel cell is producing more power than the electricvehicle propulsion system requires. The propulsion system may regeneratepower as the brakes are applied. The fuel cell then maintains output, at744, until the batteries are fully charged. At 764 the batteriesdischarge while they power a heating device to maintain operation of therefrigeration system to keep the batteries and the cabin cool. Once thebatteries discharge to a predetermined level, the fuel cell and theheating device cycle as described above. In one example, thepredetermined level is set to balance inefficient operation of the fuelcell and the cycling frequency to achieve cycling stability. In anotherexample, the integrated energy management system is programmed todistinguish a short stop from a long stop, and to maintain a cabintemperature at a comfort threshold temperature for a short time. Theshort time may be, for example, indicative of a shopping stop. The shortstop may be predicted based on travelled distance, travel profile, orGPS location, for example.

While the present disclosure has been described as having an exemplarydesign, the present disclosure may be further modified within the spiritand scope of this disclosure. For example, additional predictivefeatures may be incorporated. In a method for a mobile application, forexample, acceleration, passing and stopping profiles are defined fordifferent environments such a city, highway, mountain environments basedon vehicle displacement, acceleration and velocity. The integratedenergy management system compares present variables to the profiles toselect a profile and then utilizes the profile and other variables tooptimize operation and efficiency of the vehicle. Exemplary othervariables include the voltage of the batteries, desired cabintemperature, ambient temperature, and other operating parameters of thevehicle. In one example, the profiles include variable thresholds. Theintegrated energy management system compares profile thresholds topresent values of the corresponding variables and switches profiles whenthe present value indicates that further operation according to theprofile in place will cause a violation of a threshold. Then, theintegrated energy management system switches profiles to prevent suchviolation.

In another example, a fuel cell coupled refrigeration system is operatedbased on profiles in a stationary application. Exemplary profiles arebased on time of day, loads schedules, seasonal weather patterns, andschedules such as work and travel schedules. Thus, while the environmentin which the refrigeration system is used, and the type of refrigerationsystem, define the operating variables of the system, operationalcontrol of the coupled fuel cell provides flexibility to optimizeoperation of the integrated energy management system at different timesand for different reasons. This application is intended to cover anyvariations, uses, or adaptations of the disclosure using its generalprinciples. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this disclosure pertains.

In view of the above, it will be seen that the several advantages of thedisclosure are achieved and other advantageous results attained. Asvarious changes could be made in the above systems and methods withoutdeparting from the scope of the disclosure, it is intended that allmatter contained in the above description and shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

When introducing elements of the present disclosure or the variousversions, embodiment(s) or aspects thereof, the articles “a”, “an”,“the” and “said” are intended to mean that there are one or more of theelements. The terms “comprising”, “including” and “having” are intendedto be inclusive and mean that there may be additional elements otherthan the listed elements.

1. An integrated energy management system for generating and managingthermal energy, the system comprising: a fuel cell operable to generateelectric energy and thermal energy; an energy storage device operable toreceive at least a portion of the electric energy generated by the fuelcell; a refrigeration system including a refrigerant; a heat exchangeroperable to transfer at least a portion of the thermal energy from thefuel cell to the refrigeration system to heat the refrigerant; and acontrol system operable to control operation of the fuel cell.
 2. Aintegrated energy management system as in claim 1 further comprising aheating device thermally coupled with the refrigeration system, thecontrol system operable to cycle the fuel cell and the heating device.3. An integrated energy management system as in claim 2 furthercomprising a heating device thermally coupled with the refrigerationsystem, the control system operable to cycle the fuel cell and theheating device to drive a refrigeration cycle of the refrigerationsystem alternatively with the fuel cell and the heating device.
 4. Anintegrated energy management system as in claim 1 further comprising aplurality of operating profiles, the control system operable to select aselected profile of the plurality of operating profiles.
 5. Anintegrated energy management system as in claim 4 wherein the selectedprofile is selected to control a temperature inside a compartment.
 6. Anintegrated energy management system as in claim 1 wherein therefrigeration system comprises a compressor.
 7. An integrated energymanagement system as in claim 6 wherein the compressor is powered, atleast in part, by the fuel cell.
 8. An integrated energy managementsystem as in claim 6 wherein the control system is operable to provideelectrical energy to the compressor motor from an electrical power grid,and from the inverter device to the electrical power grid.
 9. Anintegrated energy management system as in claim 6 further comprising aheating device, the control system operable to cycle the fuel cell andthe heating device according to the selected profile.
 10. An integratedenergy management system as in claim 6 wherein the selected profile isconfigured to control the fuel cell to satisfy a target refrigerationparameter and reduce a total energy cost of the energy consumed by therefrigeration system and the fuel cell.
 11. An integrated energymanagement system as in claim 10 further including an electrical load,wherein the selected profile is configured to operate the electricalload and to reduce the total energy cost of the energy consumed by therefrigeration system, the fuel cell and the electrical load.
 12. Anintegrated energy management system as in claim 10 wherein the selectedprofile includes a first mode of operation and a second mode ofoperation, and wherein the control system is operable to maintain a highcharge level in the energy storage device in the first mode of operationand to engage the second mode of operation during times when gridsupplied electrical energy costs exceed a cost threshold.
 13. Anintegrated energy management system as in claim 1 further including anauxiliary cooling system operable to remove thermal energy from the fuelcell.
 14. A method to operate an integrated energy management system,the method comprising: generating electric energy and thermal energywith a fuel cell; storing at least a portion of the electric energy inan energy storage device; and driving a refrigeration cycle of arefrigeration system with energy provided by a first source of energyand with thermal energy from the fuel cell.
 15. A method as in claim 14further comprising changing an energy ratio between the energy providedby the first source of energy and the thermal energy responsive to avariable associated with the first source of energy.
 16. A method as inclaim 15 wherein the variable is the energy cost of the energy from thefirst source of energy, wherein the changing comprises reducing theenergy ratio when the energy cost of the energy from the first source ofenergy increases.
 17. A method as in claim 15 wherein the variable isthe energy cost of the energy from the first source of energy, whereinthe changing comprises reducing the energy ratio when the energy cost ofthe energy from the first source of energy exceeds a predetermined highcost level.
 18. A method as in claim 15 wherein the first source ofenergy is the energy storage device and the changing comprises reducingthe energy ratio when a charge level of the energy storage devicereaches a predetermined low charge level.
 19. A method as in claim 14further comprising operating the refrigeration system and the fuel cellwith an energy management system to control a building temperature, andchanging, by the energy management system, an energy ratio between theenergy provided by the first source of energy and the thermal energyresponsive to a variable associated with the first source of energy. 20.A method as in claim 19 wherein the first source of energy is anelectrical power grid, further comprising, by the energy managementsystem, reducing the ratio when an energy cost of the electrical energyfrom the electrical power grid exceeds a predetermined kilowatt-hourcost.